Deepsea Challenger: Possibly today, Guam time

Update, 10 pm CDT: Cameron sent this note via Twitter about three hours ago: 

 "I only tweet when I have something worth saying. Today is the culmination of a 7 yr project. It's finally dive day. Follow us"

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The weather forecast looks better today off Guam than over the next several days, when the trade winds will increase by 5 knots. It's Sunday morning there now. The sea is choppy with superimposed wind waves and long swells, but that's par for this time of year, so I doubt that Cameron will hold out for ideal conditions. If the sub is ready, I'd bet that he's ready too.

So if you're a Deepsea-Cameron buff like I am, stay tuned for news of the first solo dive to the Challenger Deep.

Spelling correction: the ship's physician doing most of the expedition blogs is Joe MacInnis, not McInniss. Sorry, doc!

Possible correction on last post: I'm told by an engineer not on the team that the unmanned trial of Deepsea Challenger would, more likely, have been carried out without any physical link to the surface, whether by tether (for communications) or cable (for lifting). In that case my "unlikely scenario" is the most likely one. 

If that's the case, the team would have sent the sub down relying on its on-board instruments and programmed responses, supervised by an acoustic link to the surface.

On the subject of tethers vs. cables. Long ago, mother ships used armored steel cables to keep tabs on their unmanned rovers. The sturdy ROV known as Jason, for example, depended on a composite cable more than a half-inch in diameter, with three layers of steel for hauling strength. 

WHOI's unmanned Nereus, which touched the Challenger Deep in 2009, dumped the lift cable entirely. It was tied to the surface only by a light fiber as delicate as a fishing line. Nereus carried its own power supply, and took itself up and down the water column.

A growing population of underwater craft are even further along in breaking free of the surface, and people too. These AUVs, short for autonomous underwater vehicles, can rove the sea for hours, days, or even weeks at a time before returning to base. Some AUV's can recharge on their own, at solar-panel platforms in mid-ocean. 

Ultra-efficient designs like underwater gliders are built for long range travels and don't rely on acoustic directions from the surface. Here's a paper on the subject, and a photo of whale-tracker components from Wired:

A more typical mission for AUVs has been ocean-floor mapping and water sampling. New military uses include hunting for sea-mines and enemy submarines.